1. Field of the Invention
This invention relates to for a castor, particularly to one possible to stop a castor and to prevent the castor from changing its direction at the same time by a simple pressing action on a brake button.
2. Description of the Prior Arts
A common conventional castor generally has a brake for stopping, and FIG. 1 shows a kind of known conventional castor, which includes a wheel support member 10, an axle 11, a castor 12, a pivot shaft 13, a brake plate 14 combined with the pivot shaft 13, and a press plate 15.
To put the brake on the conventional castor, the press plate 15 is pressed down to force the brake plate 14 to move down to press on the surface of the castor 12. And in releasing the brake off the castor 12, a user has to bend the body to pull up the press plate 15 so as to let the brake plate not pressing down on the castor 12, very troublesome to do. Moreover, the gap between the wheel support member and the castor 12 is too large so very slender matters such as hairs or strings, may be wound around the axle in the gap to obstacle smooth movement of the castor.
This invention has been devised to offer a brake for a castor, which is easily handled to put on the brake to the castor body and take the brake off the castor body.
The main feature of the invention is a brake unit, which consists of a brake plate, an upper brake button and a lower brake button. The brake plate is oblong, having a disc gear formed in a front portion, a projection formed on a rear portion located a little above a castor body, and two projections formed at two sides of an intermediate portion. Then the disc gear has a center hole for a threaded rod to pass through upward to be kept a little below a direction gear fixed also on the threaded rod. The lower brake button is shaped as an inverted T, having a small diameter portion and a lower large diameter portion and a center through hole for a coil spring to extend therein, The lower portion has a plurality of vertical projecting ridges spaced apart on an outer surface, and a plurality of vertical grooves interposed alternately with the projecting ridges. The lower portion has its annular upper surface is provided with a plurality of sloped surfaces to match with sloped surfaces of the upper brake button when the upper brake button is combined on the upper portion of the lower brake button. Then when the upper brake button is pressed down, the lower brake button is also moved down and rotated at the same time, with the projecting ridges also rotating from vertical grooves in a cylindrical hole where the upper brake button is located movably to hook with vertical ridges in the cylindrical hole. Then the lower brake button is in a pressed condition, pressing on the surface of the castor body, which is then stopped immovable. Thus the brake is put on the castor body. At the same time the heavier gear of the brake plate usually located a little below the direction gear will be moved up by the two projections functioning as pivots when the rear portion of the brake plate is pressed down by the lower brake button in case of the upper brake button is pressed down to put the brake on the castor body. Thus the gear of the brake plate may engage with the direction gear so that the castor body is prevented from changing its direction. In case of the brake taken off, the gear of the brake plate will move down owing to its own heavier weight than that of the rear portion of the brake plate, disengaging from the direction gear to let the castor body free to change its direction.
Further, a second feature of the invention is an orienting system for securing the direction of the castor in case of not putting the brake on the castor. The orienting system consists of a position plate, a pedal and a release plate, and is combined with the rear end of the castor-supporting member. Then the pedal is pressed down, and the position plate stops the direction gear so that the castor body is stopped, too, with the brake not put on.